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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        var s4 = new Set()
        // 添加数值
        var s3 = s4.add('a').add('b').add('c')
        console.log(s3);
        var s2 = s3.delete('c')
        console.log(s2);
        var s1 = s4.has('a')
        console.log(s1);
        var ss2 = new Set([1, 231, 2, 31, 33, 213, 23])
        ss2.forEach(value => console.log(value));
        // console.log(ss);
        
        // s4.clear();
        // console.log(s4);
    </script>
</body>

</html>